Meteorite analysis

Nasa has a nice set on meteorite landings. See the source of the data here.

library(dplyr)
library(readr)
library(leaflet)
library(ggplot2)
library(knitr)
library(plotly)

Import data

The data is a plain csv file. We create a proper date column, rename mass (g) and create a mass in kilograms.

meteorites <- read_csv(
  "Meteorite_Landings.csv", 
  col_types = cols(year = col_character())
) %>% 
  rename (mass = `mass (g)` ) %>% 
  mutate( 
    mass_kg = mass / 1000,
    date =  as.POSIXct(year,format="%d/%m/%Y %H:%M:%OS"), 
    recency = 2020 - lubridate::year(date)
  )

kable(head(meteorites, 7))
name id nametype recclass mass fall year reclat reclong GeoLocation mass_kg date recency
Aachen 1 Valid L5 21 Fell 01/01/1880 12:00:00 AM 50.77500 6.08333 (50.775, 6.08333) 0.021 1880-01-01 12:00:00 140
Aarhus 2 Valid H6 720 Fell 01/01/1951 12:00:00 AM 56.18333 10.23333 (56.18333, 10.23333) 0.720 1951-01-01 12:00:00 69
Abee 6 Valid EH4 107000 Fell 01/01/1952 12:00:00 AM 54.21667 -113.00000 (54.21667, -113.0) 107.000 1952-01-01 12:00:00 68
Acapulco 10 Valid Acapulcoite 1914 Fell 01/01/1976 12:00:00 AM 16.88333 -99.90000 (16.88333, -99.9) 1.914 1976-01-01 12:00:00 44
Achiras 370 Valid L6 780 Fell 01/01/1902 12:00:00 AM -33.16667 -64.95000 (-33.16667, -64.95) 0.780 1902-01-01 12:00:00 118
Adhi Kot 379 Valid EH4 4239 Fell 01/01/1919 12:00:00 AM 32.10000 71.80000 (32.1, 71.8) 4.239 1919-01-01 12:00:00 101
Adzhi-Bogdo (stone) 390 Valid LL3-6 910 Fell 01/01/1949 12:00:00 AM 44.83333 95.16667 (44.83333, 95.16667) 0.910 1949-01-01 12:00:00 71

Data exploration

logg mass

The mass of the meteorite is recorded. Below you see a histogram of the mass_kg (log 10 scale). so log_mass_kg = 0 means the meteorite had a mass of 1 KG.

meteorites = meteorites %>% 
  filter( recency >= 0) %>% 
  mutate(
    log_mass_kg = log10(mass_kg)
  )
ggplot(meteorites, aes(x=log_mass_kg)) + geom_histogram(col = "black")

Time series

The following plots shows the mass of the meteorite versus date of landing

mass in KG
meteorites %>% ggplot(aes(x = date, y = mass_kg)) + geom_line()

log mass
meteorites %>% ggplot(aes(x = date, y = log_mass_kg)) + geom_line()

Recency in years

For most, not all, the date of the landing is recorded. The following histogram shows how recent the landing was (in years).

meteorites = meteorites %>% 
  filter( recency >= 0, recency < 200)

ggplot(meteorites, aes(x=recency)) + geom_histogram(col = "black", binwidth = 5)

Meteorite class

mclasses = meteorites %>% 
  group_by(recclass) %>%
  summarise(n=n()) %>%
  arrange(desc(n)) %>% 
  head(30) 


#  ggplot(aes(recclass, weight = n)) +
#  geom_bar()

plot_ly(mclasses, x=~recclass, y = ~n )
## No trace type specified:
##   Based on info supplied, a 'bar' trace seems appropriate.
##   Read more about this trace type -> https://plot.ly/r/reference/#bar

Leaflet map

Interactive map of astroid locations.

reds <- colorNumeric("Reds", domain = NULL)

labels = paste(sep = "<br>", meteorites$name, lubridate::year(meteorites$date))
leaflet(
  data = meteorites, 
  width = "1400px", height = "1100px",
  ) %>% 
  addTiles() %>%
  setView(5,50, zoom = 5) %>% 
  addCircleMarkers(
    ~reclong, ~reclat,
    label = ~labels, 
    radius = ~log_mass_kg,stroke = TRUE, weight = 2,
    fillOpacity = .75,
    color = ~reds(recency)
  ) %>% 
  addLegend(
    pal = reds,
    values = ~recency, 
    group = "circles", position = "bottomleft", title = "recency (in years)"
  )